Research On The Seed Germination And Seedling Growth Characteristics Of Metasequoia Glyptostroboides

Metasequoia glyptostroboides Hu et Cheng is a Tertiary relic plant and endemic species in China. Its nature community only distribute in the Lichun of Hubei province which lack seedlings and saplings, so the nature regeneration of community is difficult. We chose three environmental factors of groundwater level, light intensity and burial depth. And then set some different gradients respectively, to research the effect of these three environmental factors on seed germination and seedling growth of M. glyptostroboides.In the study of effect of different groundwater level on seed germination and seeding growth of Metasequoia glyptostroboides, we set six water level gradients (1.0、0、-4、-8、-12 and -16 cm). The results showed that the seed germination rate was highest (55.5±3.42%) at 0 cm water level. When the water level was -16 cm, the seed didn’t germinate. And when the water level was above the soil surface (1.0 cm), the seed also didn’t germinate. Similarly, when the water level was 0 cm, the seedling grew best, that seedling height, leaf number and biomass were significantly higher than the other water levels. That indicated that higher water level is more suitable for seed germination and seedling growth of M. glyptostroboides.In the study of effect of different burial depth on seed germination and seeding growth of Metasequoia glyptostroboides, we set six burial depth gradients (-0.5、0、0.5、1.0、1.5 and 2.0 cm). The results showed that the seed germination rate was highest (56±3.26%) at 0 cm burial depth. The seed germination rate decreased significantly with decreased water level. Seeds did not germination when seeds were buried 2 cm deep. And when the burial depth was 0 cm, the seedling growth condition was best. As the burial depth increases, the height, leaf number and biomass of seedling declined. When the burial depth was -0.5 cm, the seed germination rate is 46±3.30%. In this condition the seeds floated on the water, the seedlings root could not plant, so the seedlings gradually died. That indicated no burial condition is more suitable for seed germination and seedling growth of M. glyptostroboides.In the study of effect of different light intensity on seed germination and seeding growth of Metasequoia glyptostroboides, we set five light gradient treatments (100%、72.16%、44.16%、25.40% and 6.14% natural light) in the field. The results showed that as the light intensity increases, the seed germination rate decreased significantly. Under the 6.14% natural light condition, the seed germination rate of M. glyptostroboides was highest (51±3.61%). On the conditions of 25.40% natural light, seedlings grew best than other conditions, that all morphology indexes and biomass of seedling have reached the maximum. When the light intensity was too strong or too weak, the growth of seedlings was not good. These results indicated that low light condition is propitious to seed germination of M. glyptostroboides, and the seedling growth need moderate intensity light conditions.Finally, the results show that the seed germination and growth and colonization of seedling of M. glyptostroboides require a higher water level, no burial and moderate-intensity light conditions. The results suggest that the reasons for the lack of seedlings and saplings and difficultly nature regeneration of the M. glyptostroboides nature community are deep buried when the seeds fall, low water level and high understory light intensity of the situ of M. glyptostroboides. These conditions are bad for seed germination and growth and colonization of seedling of M.glyptostroboides.